"Isa will have an opportunity to speak for himself in due course but as soon as we became aware that he was keen on a return it was something that we have worked hard to get over the line.

"We mentioned a few weeks back how our resources will be tested during the World Cup window and to be able to bring in a top quality player who we know will contribute massively to the environment when the more experienced lads are away, is huge for us. When those guys are back, he'll drive it even more. To have Isa return on the back of the news that Johnny is also coming back and Mick Kearney signing, it's been a huge few weeks for us as we look to build for next season."

Nacewa has been involved with Auckland in a coaching capacity of late but he will only be working for Leinster in a playing capacity.

"Obviously, I'm very excited to be going back to Leinster," Nacewa said on the site. "I spent five brilliant seasons there both on and off the pitch and while the decision to leave was right at the time, I also feel now that at 32 years I've still got something to give. If I didn't grab this opportunity, there will always be a sense of 'what if'.

"I am very grateful to John Kirwan and everyone at the Blues for the opportunity of working with them over the last two seasons. It's not a decision Simone and I came to lightly, but we can't wait to get back there and see what comes of it.

"I've had a number of chats with Matt obviously around my role but ultimately I just can't wait to get back onto the pitch, training and playing and of course running out at a full RDS."

Nacewa won three European Cups with the province in his first stint so Leinster fans will be hoping he can bring that sort of glory day back to the RDS.